The present invention relates to a vehicular wheel chock assembly and method of operation, and more particularly, to such an assembly and method for use in providing automatic, positive chocking of one or more wheel of a vehicle upon setting of the vehicle""s parking brakes and automatic retraction of the chock assembly upon release of the parking brakes.
Modem vehicles are normally supplied with emergency or parking brake systems that function to maintain the vehicle in a fixed position. Such systems usually operate on the wheels of the vehicle and are intended to prevent the wheels from rotating while the vehicle is parked and to thereby prevent the vehicle from accidentally moving.
Commercially used cargo vehicles, such as trucks or trailers of a tractor-trailer combination, are also provided with supplemental systems for preventing wheel rotation and vehicle movement. Typically, such vehicles carry wedge shaped, wheel chocks that are to be manually placed in front and/or behind a tire mounted on a wheel of the vehicle when it is parked. In many cases, the use of such tire engaging wheel chocks is mandated by government regulation or regulations of the trucking firm or its clients. For example, state and federal regulations, as well as company or trucking firm rules, require that drivers of vehicles, e.g. single axle delivery trucks, place at least one wheel chock forward and one wheel chock rearward of a drive wheel tire at every stop that the vehicle makes. Each wheel chock is hand wedged against the tire and ground or pavement surface. Although the wheel chocks contact and are wedged between the tire surface and the ground or pavement, they are customarily referred to as xe2x80x9cwheel chocksxe2x80x9d rather than xe2x80x9ctire chocksxe2x80x9d.
While the consistent and correct use of such wheel chocks serves the function of preventing runaway of a vehicle, chocks are not always available when the vehicle is parked or the driver may forget to place them in position or may place them improperly. An improperly placed wheel chock may also slip or move aside if the vehicle is jarred or is on an incline. The failure to place a wheel chock or the failed function of the wheel chock can result in property damage and/or personal injury and/or the imposition of sanctions against the driver and his employer. If hazardous materials are involved, environmental damage and personal injury of others can also result.
Over the years, many attempts have been made to provide a mechanized wheel chock assembly wherein one or more wheel chock is lowered into position when the vehicle is parked and raised before the vehicle is driven away as typified by U.S. Pat. Nos. 3,086,619, 3,176,798, 3,517,776 and 4,354,580. A wheel blocking mechanism is also described in U.S. Pat. No. 5,601,158 which is used for the same purpose but engages only into the tire to prevent it from rotating and does not engage the surface the tire rests upon. Emergency braking systems are disclosed in U.S. Pat. Nos. 4,949,817, 5,435,418, 5,439,076, and 5,497,857 that deploy brake wedges similar to wheel chocks or flaps while the vehicle is moving to slow it when the regular brakes fail or otherwise cannot stop the vehicle.
To my knowledge, these systems have not been widely commercialized, and drivers still rely upon use of hand deployed wheel chocks to stabilize a parked vehicle.
The present invention has a number of aspects which may be advantageously employed separately or in combinations which in turn may be separately claimed or claimed in combination.
One aspect of the present invention provides an improved control system for deploying and retracting an improved wheel chocking apparatus that can be installed on a truck or trailer and operated by the vehicle driver sitting in the driver""s seat.
Another aspect of the present invention provides a vehicle wheel chock assembly attached to a vehicle in a position to be stored in a retracted position in a compact configuration that can be deployed to force two or more wheel chocks into an engaged position in engagement between a tire of the vehicle and the surface it rests upon to prevent rotation of the tire.
Another aspect of the present invention provides various ways of utilizing the vehicle pressurized air supply to operate the wheel chock assembly between and in the retracted position and the engaged position.
Another aspect of the present invention incorporates a particular wheel chock configuration and mounting that maintains it in a relatively clean state that facilitates its deployment into the engaged position.
In one aspect of the invention, the improved control system is operable in conjunction with the setting and releasing of the vehicle""s emergency or parking brakes such that two or more wheel chocks are deployed from their retracted positions to their engaged positions upon setting the brakes and are retracted from their engaged positions back to their retracted positions upon release of the brakes. Preferably, the vehicle driver only has to set or release the brakes to cause the wheel chock(s) to be deployed or retracted, respectively.
Moreover, positive forces are employed to maintain the wheel chocks in both the retracted and deployed position. In a further aspect of the invention, the positive forces are supplied by the vehicle""s accessory air supply.
In a particular embodiment, front or forward and rear or back wheel chocks are mounted at the free ends of articulated, front and rear, chock deployment and retraction arms, or chock arms, respectively. The fixed ends of the front and rear chock arms are coupled to respective front and rear arm axles that are mounted to the vehicle parallel with the vehicle axle and located forward and rearward of the vehicle wheel that the wheel chocks engage in the deployed or engaged position. Front and rear pivot arms are fixedly coupled at fixed pivot arm ends to the front and rear arm axles and extend to front and rear pivot arm free ends, respectively. A dual action pneumatic air cylinder having a fixed end and a movable piston rod at the other end is mounted between the front and rear pivot arm free ends and thereby extends perpendicularly to and is coupled between the front and rear arm axles. The mountings of the cylinder fixed end with the front pivot arm and the piston rod free end with the rear pivot arm free end allow the front and rear pivot arms to be pivoted about the front and rear arm axles and to thereby rotate the front and rear arm axles upon extension and retraction of the piston arm from and back into the cylinder. The mutual rotations of the front and rear arm axles in turn causes the front and rear chock arms to pivot between the engaged and retracted positions.
The dual action pneumatic air cylinder has a cylinder extension air inlet/outlet to an extension chamber on an extension side of an internally disposed piston within the cylinder coupled with the piston rod and a cylinder retraction air inlet/outlet to a retraction chamber on a retraction side of the internally disposed piston within the cylinder through which the piston rod extends to its free end. The piston rod is extended by movement of the piston in the elongated cylinder bore away from the cylinder fixed end when extension air pressure applied to the extension air inlet/outlet exceeds retraction air pressure applied to the retraction air inlet/outlet or retraction air pressure is bled from the retraction air inlet/outlet. Similarly, the piston rod is retracted by movement of the piston in the elongated cylinder bore away toward the cylinder fixed end when retraction air pressure applied to the retraction air inlet/outlet exceeds extension air pressure applied to the extension air inlet/outlet or extension air pressure is bled from the extension air inlet/outlet.
In accordance with a further aspect of a first embodiment of the present invention, the retraction and extension air pressures are derived from the vehicle accessory air supply. In preferred embodiments of the invention, the air pressure is supplied by an air reservoir tank that supplies air to the extension air inlet/outlet upon engagement of the emergency/parking brake and to the retraction air inlet/outlet upon release, respectively, of the vehicle""s air powered parking or emergency brakes.
Thus, the vehicle driver merely has to engage the emergency/parking brake when parking the vehicle to cause the wheel chocks to be moved from their retracted positions to their engaged positions in front of and behind a vehicle wheel. The wheel chock assembly positively forces the wheel chocks into engagement with the parked vehicle wheels and the surface they rest on or positively collapses the chock assembly into a compact, retracted, stored configuration.
Advantageously, the movement between the retracted and engaged positions is at a relatively slow rate to avoid accidental injury to technicians engaged in service or repairs. Moreover, if the driver engages the emergency brake while the vehicle is moving, the delayed deployment from the retracted position to the engaged position allows the wheel brakes to be engaged and locked up during the delay. Then, the wheel chocks will contact a stopped wheel, and at least the forward wheel chock will be frictionally engaged with the ground surface to assist in stopping the vehicle or trailer.
Furthermore, the wheel chocks are mounted and configured to shed any accumulation of material that would interfere with their safe deployment while in the retracted position. Specifically, the wheel chocks are cylindrical and mounted to the free end of the chock arms to rotate about an axis parallel with the wheel axis while in the retracted position so that any accumulation of mud, dirt, snow, road slush or ice or other material upon is shed or tends to be dropped off, thereby keeping the wheel chock clean and able to be deployed into the engaged position when needed.
The foregoing Summary of the Invention is not intended to describe each embodiment or every implementation of the present invention. While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail hereinbelow. It is to be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.